Adenosine triphosphate (ATP)	A chemical compound that contains ‘energy-rich bonds’ and is used by cells to store and deliver energy
Aerobic organism	An organism that requires free oxygen for life and growth
Alcohol-based hand rub	A hand decontamination preparation based on alcohol that, for the purposes of these guidelines, encompasses solutions, gels or wipes
Antimicrobial	A substance that kills or inhibits the growth of microorganisms
Asepsis	The absence of pathogenic microorganisms
Antiseptic	A substance that destroys or inhibits the growth of microorganisms and is sufficiently non-toxic to be applied to skin or mucous membranes
Aseptic non-touch technique (ANTT)	A framework for the aseptic technique based on the concept of defining key parts and key sites to be protected from contamination.
Aseptic technique	A carefully controlled procedure that aims to prevent contamination by microorganisms
Bacteraemia	The presence of microorganisms in the bloodstream
Bacteriuria	The presence of microorganisms in the urine. If there are no symptoms of infection, this is called ‘asymptomatic bacteriuria’
Biofilm	A complex structure comprising microorganisms and extracellular polymers that forms over surfaces, such as those in contact with water or tissues
Bladder irrigation	Continuous flow of a solution through the bladder to remove clots or debris
Bloodborne virus	A viral infection transmitted by exposure to blood and sometimes other bodily fluids. Bloodborne viruses include hepatitis B and C as well as human immunodeficiency virus
Bloodstream infection (BSI)	The presence of microbes in the blood with symptoms of infection
Case-control study	An analytical observational study that compares people with the disease of interest with a group of similar ‘control’ people who do not in order to determine potential causes or risk factors
Case report	A scientific article that describes an individual case in detail
Case series	A report describing a series of several similar events
Catheter-associated urinary tract infection (CAUTI)	The presence of symptoms or signs attributable to microorganisms that have invaded the urinary tract, where the patient has, or has recently had, a urinary catheter
Catheter colonisation	Microorganisms present on a surface of a catheter that could potentially lead to infection
Catheter-related bloodstream infection (CR-BSI)	An infection of the bloodstream where microorganisms are found in the blood of a patient with a central venous access device, the patient has clinical signs of infection (e.g. fever, chills and hypotension) and there is no other apparent source for the infection. For surveillance purposes, this often refers to bloodstream infections that occur in patients with a central venous access device and where other possible sources of infection have been excluded. A more rigorous definition is where the same microorganism is cultured from the tip of the catheter as grown from the blood; simultaneous quantitative blood cultures with at least a 5:1 ratio of microorganisms cultured from the central venous access device vs peripheral; differential time to positivity of at least 2 h for blood cultures cultured peripherally vs from central venous access device
Catheter-related infection	Any infection related to a central venous access device, including local (e.g. insertion site) and systemic (e.g. bloodstream) infections
Central venous catheter (CVC)	A vascular catheter inserted with the tip located in the superior vena cava. Central venous catheters are used for giving multiple infusions, medication or chemotherapy, temporary haemodialysis, monitoring of central venous pressure and frequent blood sampling
Chlorhexidine	An antiseptic widely used as a solution to disinfect and cleanse the skin, wounds or burns
Cleaning	Methods that physically remove soil, dust and dirt from surfaces or equipment
Clinical waste	Waste material that consists wholly or partly of human or animal tissue, blood or body fluids, excretions, drugs or other pharmaceutical products, swabs/dressings, syringes, needles or other sharp instruments
Closed urinary drainage system	A system where a urinary catheter is connected via tubing to a collecting bag. The system relies on gravity to drain the urine
Cohort study	A prospective or retrospective follow-up study where groups to be followed-up are defined on the basis of presence or absence of exposure to a risk factor or intervention
Colonisation	Microorganisms that establish themselves in a particular environment, such as a body surface, without producing disease
Colony-forming unit (cfu)	An estimate of the number of viable bacterial cells made by counting visible colonies derived from the replication of a single microbial cell
Cross-infection	Transmission of a pathogenic organism from one person to another
Crossover trial	A comparison of the outcome between two or more groups of patients that are exposed to different regimens of treatment/intervention where the groups exchange treatment/intervention after a pre-arranged period
Decontamination	A process that removes hazardous substances, including chemicals or microorganisms
Detergent	A cleansing agent that removes dirt from a surface by bonding with lipids and other particles
Disinfection	A process that reduces the number of pathogenic microorganisms to a level at which they are not able to cause harm, but which does not usually destroy spores
Droplet nuclei	Particles 1–10 μm in diameter comprising the dried residue formed by evaporation of droplets coughed or sneezed from the respiratory tract
Dysuria	Difficult or painful urination
Encrustation	Urinary proteins, salts and crystals that adhere to the internal and external surface of a urinary catheter
Engineering controls	The use of equipment designed to prevent injury to the operator
Enteral feeding	Administration of nutrients into stomach or other part of the gastrointestinal tract using tubes
Exogenous infection	Infections caused by microorganisms acquired from another person, animal or the environment
Expert opinion	Opinion derived from seminal works and appraised national and international guidelines
Gram-negative/-positive bacteria	The type of bacteria as identified by Gram's staining method. Gram-positive bacteria appear dark blue or purple under a microscope. Such bacteria have a thick layer of peptidoglycan on their cell walls. Gram-negative bacteria appear red under a microscope and have an outer layer of lipoprotein and a thin layer of peptidoglycan
Guidewire	A wire used to facilitate insertion of the intravascular catheter into the body
Haemothorax	Blood in the pleural cavity, usually due to injury. If the blood is not drained, it may impair the movement of the lungs or become infected
Haematogenous seeding	Microorganisms causing infection establish infection at another body site as a result of being transferred in the bloodstream
Hand decontamination or hand hygiene	The use of soap and water or an antiseptic solution to reduce the number of microorganisms on the hands
Hawthorne effect	A phenomenon in which the participants change their behaviour or performance in response to being studied
Healthcare-associated infection (HCAI)	Infection acquired as a result of the delivery of health care either in an acute (hospital) or non-acute setting
Healthcare worker	Any person employed by a health service, social service, local authority or agency to provide care for sick, disabled or elderly people
Heterogeneity	Variability, difference
Hyperalimentation	The administration of nutrients intravenously, usually to individuals who cannot take food via the gastrointestinal tract
Hypochlorite	A chlorine-based disinfectant
Implantable intravascular device	A central venous access device that is tunnelled under the skin with a subcutaneous port or reservoir with a self-sealing septum that is accessible by needle puncture through intact skin
Incidence	The number of new events (e.g. cases of disease) occurring in a population over a defined period of time
Indwelling urethral catheter	A catheter inserted into the bladder via the urethra and left in place for a period of time
Infection	Microorganisms that have entered the body and are multiplying in the tissues, typically causing specific symptoms
Intention-to-treat analysis	An analysis in which the results of the study are based on initial treatment assignment and not on a treatment actually received
Interrupted time series	A study in which measurements from the group under investigation are taken repeatedly before and after the intervention
Intravascular access device (IVAD)	A device inserted into a vascular system in order to administer fluids, medicines and nutrients or to obtain blood samples. These include devices inserted peripherally, as well as those inserted into larger veins
Invasive device	Any device that requires insertion through skin or other normal body defences
Luer connector	A system of attaching catheters, syringes, tubes and any other components of IVAD to each other
Meatus (urethral)	External opening of the urethra
MeSH	Medical subject heading
Meta-analysis	The combination of data from several studies to produce a single estimate of an effect of a particular intervention
Meticillin-resistant Staphylococcus aureus (MRSA)	Strains of S. aureus that are resistant to many of the antibiotics commonly used to treat infections. Epidemic strains also have a capacity to spread easily from person to person
Midline catheter	A long peripheral venous catheter inserted in the antecubital vein and advanced to a vein in the upper arm. Designed for short-term (up to 4 weeks) intravenous access
Mucosa	A membrane lining many tubular structures and cavities such as respiratory tract
Needle-free devices (also needleless intravascular catheter connectors)	Intravascular connector systems developed to help reduce the incidence of needlestick injury while facilitating medication delivery through intravascular catheters. There are three types of needle-free connectors: blunt cannula (two-piece) systems, one-piece needle-free systems, and one-piece needle-free systems with positive pressure
Needle safety device (also needle protection/prevention device)	Any device designed to reduce the risk of injury associated with a contaminated needle. This may include needle-free devices or mechanisms on a needle, such as an automated resheathing device, that cover the needle immediately after use
Needlestick injury	The puncture of skin by a contaminated needle or other sharp medical device
Neutropenia	Abnormal decrease in the number of neutrophils in peripheral blood, which results in increased susceptibility to infections
Nitrile	A synthetic rubber made from organic compounds and cyanide
Observational study	A retrospective or prospective study in which the investigator observes participants, with or without control groups
Organic matter	Any derivative of a living or once-living organism
Outbreak	Two or more cases of the same disease where there is evidence of an epidemiological link between them
Parenteral feeding (intravenous feeding)	Administration of nutrients by an infusion into a vein
Particulate filter masks (or respirator masks)	Face masks designed to protect the wearer from inhaling airborne particles including microorganisms. They are made to defined performance standards that include filtration efficiency. To be effective, they must be fitted close to the face to minimise leakage
Pathogen	A microorganism that causes disease
Peer-reviewed research	An independent assessment or evaluation of the research by a professional with knowledge of the field
Percutaneous injury	An injury that results in a sharp instrument/object (e.g. needle, scalpel) puncturing the skin
Peripheral inserted central venous catheter (PICC)	A vascular catheter inserted into the superior vena cava from the basilic or cephalic vein
Personal protective equipment (PPE)	Specialised clothing or equipment worn to protect against substances or situations that present a hazard to health or safety
Phlebitis	Inflammation of a vein
Post-exposure prophylaxis	Drug treatment regimen administered as soon as possible after an occupational exposure to reduce the risk of acquisition of a bloodborne virus
Povidone iodine	A topical preparation used for antisepsis of the skin in a form of solution or ointment
Prevalence	The number of events (e.g. cases of disease) present in a defined population at one point in time
Prospective study	Study in which people are entered into the research and then followed-up over a period of time with events recorded as they happen
Peripheral venous catheter (PVC)	A small, flexible tube placed into a peripheral vein for the safe infusion of medications, hydration fluids, blood products and nutritional supplements
Quasi-experimental study	Quasi-experimental research designs specifically lack the element of random assignment of participants (individuals or clinical settings/units) to the treatment or the control group. Randomisation minimises the risk that patients entered into the control and treatment groups will be different
Randomised controlled trial (RCT) and non-randomised controlled trial (NRCT)	An RCT is a clinical trial where at least two treatment groups are compared, one of them serving as the control group. Allocation to the group uses a random, unbiased method. An NRCT compares a control and treatment group but allocation to each group is not random. Bias is more likely to occur in an NRCT
Resident (hand) flora	Microorganisms that live in the deeper crevices of skin and hair follicles. These form part of the normal flora of the body and are not readily transferred to other people or objects, or removed by the mechanical action of soap and water. They can be reduced in number with the use of antiseptic soap
Respirator	See ‘particulate filter masks’
Retrospective study	A study in which data are captured from historical records of exposures and disease
Sepsis	A severe, systemic reaction of the immune system to infection that can result in organ failure and death
Severe acute respiratory syndrome (SARS)	A severe form of pneumonia caused by a coronavirus
Sharps	Instruments used in delivering health care that can inflict a penetrating injury. Examples include needles, lancets and scalpels
Spore	A resistant structure produced by microorganisms that enable it to survive adverse conditions
Sterilisation	A process that removes or destroys all microorganisms including spores
Surgical masks	A mask that covers the mouth and nose to prevent droplets from the wearer being expelled into the environment. As they are also fluid repellent, they provide some protection for the wearer against exposure of mucous membranes to splashes of blood/body fluid
Systematic review	Research that summarises the evidence on a clear question according to a defined protocol using explicit and systematic methods to identify, select and appraise relevant studies and extract, collate and report their findings
Systemic infection	An infection where the pathogen is distributed throughout the body, rather than being concentrated in one area
Terminal cleaning	The decontamination of a room or patient area after a patient has been transferred or discharged in order to ensure that any dirt, dust or contamination by potentially pathogenic microorganisms is removed before use by another patient
Thrombocytopenia	A reduction in the number of platelets (thrombocytes) in the blood. This may result in bleeding into the skin, spontaneous bruising or prolonged bleeding after injury
Thrombosis	A clot in a blood vessel caused by coagulation of blood
Thrombophlebitis	Phlebitis (vein inflammation) related to a thrombus (blood clot)
Transient (hand) flora	Microorganisms acquired on the skin through contact with surfaces. The hostile environment of skin means that they can usually only survive for a short time, but they are readily transferred to other surfaces touched. Can be removed by washing with soap and water, and most are destroyed by alcohol-based hand rubs
Urinary tract infection (UTI)	The invasion of the tissues of the bladder by microorganisms causing symptoms or signs of infection such as dysuria, loin pain, suprapubic tenderness, fever, pyuria and confusion